kernel.git/arch/arm64/kernel/fpsimd.c, branch linux-4.19.y

arm64/sve: Use correct size when reinitialising SVE state

2021-09-22T09:48:10Z

commit e35ac9d0b56e9efefaeeb84b635ea26c2839ea86 upstream. When we need a buffer for SVE register state we call sve_alloc() to make sure that one is there. In order to avoid repeated allocations and frees we keep the buffer around unless we change vector length and just memset() it to ensure a clean register state. The function that deals with this takes the task to operate on as an argument, however in the case where we do a memset() we initialise using the SVE state size for the current task rather than the task passed as an argument. This is only an issue in the case where we are setting the register state for a task via ptrace and the task being configured has a different vector length to the task tracing it. In the case where the buffer is larger in the traced process we will leak old state from the traced process to itself, in the case where the buffer is smaller in the traced process we will overflow the buffer and corrupt memory. Fixes: bc0ee4760364 ("arm64/sve: Core task context handling") Cc: # 4.15.x Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20210909165356.10675-1-broonie@kernel.org Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: sve: Fix build failure when ARM64_SVE=y and SYSCTL=n

2020-07-01T03:17:15Z

[ Upstream commit e575fb9e76c8e33440fb859572a8b7d430f053d6 ] When I squashed the 'allnoconfig' compiler warning about the set_sve_default_vl() function being defined but not used in commit 1e570f512cbd ("arm64/sve: Eliminate data races on sve_default_vl"), I accidentally broke the build for configs where ARM64_SVE is enabled, but SYSCTL is not. Fix this by only compiling the SVE sysctl support if both CONFIG_SVE=y and CONFIG_SYSCTL=y. Cc: Dave Martin Reported-by: Qian Cai Link: https://lore.kernel.org/r/20200616131808.GA1040@lca.pw Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: nofpsmid: Handle TIF_FOREIGN_FPSTATE flag cleanly

2020-02-19T18:51:54Z

commit 52f73c383b2418f2d31b798e765ae7d596c35021 upstream We detect the absence of FP/SIMD after an incapable CPU is brought up, and by then we have kernel threads running already with TIF_FOREIGN_FPSTATE set which could be set for early userspace applications (e.g, modprobe triggered from initramfs) and init. This could cause the applications to loop forever in do_nofity_resume() as we never clear the TIF flag, once we now know that we don't support FP. Fix this by making sure that we clear the TIF_FOREIGN_FPSTATE flag for tasks which may have them set, as we would have done in the normal case, but avoiding touching the hardware state (since we don't support any). Also to make sure we handle the cases seemlessly we categorise the helper functions to two : 1) Helpers for common core code, which calls into take appropriate actions without knowing the current FPSIMD state of the CPU/task. e.g fpsimd_restore_current_state(), fpsimd_flush_task_state(), fpsimd_save_and_flush_cpu_state(). We bail out early for these functions, taking any appropriate actions (e.g, clearing the TIF flag) where necessary to hide the handling from core code. 2) Helpers used when the presence of FP/SIMD is apparent. i.e, save/restore the FP/SIMD register state, modify the CPU/task FP/SIMD state. e.g, fpsimd_save(), task_fpsimd_load() - save/restore task FP/SIMD registers fpsimd_bind_task_to_cpu() \ - Update the "state" metadata for CPU/task. fpsimd_bind_state_to_cpu() / fpsimd_update_current_state() - Update the fp/simd state for the current task from memory. These must not be called in the absence of FP/SIMD. Put in a WARNING to make sure they are not invoked in the absence of FP/SIMD. KVM also uses the TIF_FOREIGN_FPSTATE flag to manage the FP/SIMD state on the CPU. However, without FP/SIMD support we trap all accesses and inject undefined instruction. Thus we should never "load" guest state. Add a sanity check to make sure this is valid. Cc: stable@vger.kernel.org # v4.19 Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Ard Biesheuvel Reviewed-by: Catalin Marinas Acked-by: Marc Zyngier Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: move sve_user_{enable,disable} to

2018-07-12T13:40:39Z

In subsequent patches, we'll want to make use of sve_user_enable() and sve_user_disable() outside of kernel/fpsimd.c. Let's move these to where we can make use of them. To avoid ifdeffery in sequences like: if (system_supports_sve() && some_condition) sve_user_disable(); ... empty stubs are provided when support for SVE is not enabled. Note that system_supports_sve() contains as IS_ENABLED(CONFIG_ARM64_SVE), so the sve_user_disable() call should be optimized away entirely when CONFIG_ARM64_SVE is not selected. To ensure that this is the case, the stub definitions contain a BUILD_BUG(), as we do for other stubs for which calls should always be optimized away when the relevant config option is not selected. At the same time, the include list of is sorted while adding . Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Reviewed-by: Dave Martin Cc: Will Deacon Signed-off-by: Will Deacon

arm64: kill change_cpacr()

2018-07-12T13:40:39Z

Now that we have sysreg_clear_set(), we can use this instead of change_cpacr(). Note that the order of the set and clear arguments differs between change_cpacr() and sysreg_clear_set(), so these are flipped as part of the conversion. Also, sve_user_enable() redundantly clears CPACR_EL1_ZEN_EL0EN before setting it; this is removed for clarity. Signed-off-by: Mark Rutland Reviewed-by: Dave Martin Acked-by: Catalin Marinas Cc: James Morse Cc: Will Deacon Signed-off-by: Will Deacon

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2018-06-12T18:34:04Z

Pull KVM updates from Paolo Bonzini: "Small update for KVM: ARM: - lazy context-switching of FPSIMD registers on arm64 - "split" regions for vGIC redistributor s390: - cleanups for nested - clock handling - crypto - storage keys - control register bits x86: - many bugfixes - implement more Hyper-V super powers - implement lapic_timer_advance_ns even when the LAPIC timer is emulated using the processor's VMX preemption timer. - two security-related bugfixes at the top of the branch" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (79 commits) kvm: fix typo in flag name kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor access KVM: x86: pass kvm_vcpu to kvm_read_guest_virt and kvm_write_guest_virt_system KVM: x86: introduce linear_{read,write}_system kvm: nVMX: Enforce cpl=0 for VMX instructions kvm: nVMX: Add support for "VMWRITE to any supported field" kvm: nVMX: Restrict VMX capability MSR changes KVM: VMX: Optimize tscdeadline timer latency KVM: docs: nVMX: Remove known limitations as they do not exist now KVM: docs: mmu: KVM support exposing SLAT to guests kvm: no need to check return value of debugfs_create functions kvm: Make VM ioctl do valloc for some archs kvm: Change return type to vm_fault_t KVM: docs: mmu: Fix link to NPT presentation from KVM Forum 2008 kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation KVM: x86: hyperv: declare KVM_CAP_HYPERV_TLBFLUSH capability KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation KVM: introduce kvm_make_vcpus_request_mask() API KVM: x86: hyperv: do rep check for each hypercall separately ...

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2018-06-08T18:10:58Z

Pull arm64 updates from Catalin Marinas: "Apart from the core arm64 and perf changes, the Spectre v4 mitigation touches the arm KVM code and the ACPI PPTT support touches drivers/ (acpi and cacheinfo). I should have the maintainers' acks in place. Summary: - Spectre v4 mitigation (Speculative Store Bypass Disable) support for arm64 using SMC firmware call to set a hardware chicken bit - ACPI PPTT (Processor Properties Topology Table) parsing support and enable the feature for arm64 - Report signal frame size to user via auxv (AT_MINSIGSTKSZ). The primary motivation is Scalable Vector Extensions which requires more space on the signal frame than the currently defined MINSIGSTKSZ - ARM perf patches: allow building arm-cci as module, demote dev_warn() to dev_dbg() in arm-ccn event_init(), miscellaneous cleanups - cmpwait() WFE optimisation to avoid some spurious wakeups - L1_CACHE_BYTES reverted back to 64 (for performance reasons that have to do with some network allocations) while keeping ARCH_DMA_MINALIGN to 128. cache_line_size() returns the actual hardware Cache Writeback Granule - Turn LSE atomics on by default in Kconfig - Kernel fault reporting tidying - Some #include and miscellaneous cleanups" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (53 commits) arm64: Fix syscall restarting around signal suppressed by tracer arm64: topology: Avoid checking numa mask for scheduler MC selection ACPI / PPTT: fix build when CONFIG_ACPI_PPTT is not enabled arm64: cpu_errata: include required headers arm64: KVM: Move VCPU_WORKAROUND_2_FLAG macros to the top of the file arm64: signal: Report signal frame size to userspace via auxv arm64/sve: Thin out initialisation sanity-checks for sve_max_vl arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests arm64: KVM: Add ARCH_WORKAROUND_2 support for guests arm64: KVM: Add HYP per-cpu accessors arm64: ssbd: Add prctl interface for per-thread mitigation arm64: ssbd: Introduce thread flag to control userspace mitigation arm64: ssbd: Restore mitigation status on CPU resume arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation arm64: ssbd: Add global mitigation state accessor arm64: Add 'ssbd' command-line option arm64: Add ARCH_WORKAROUND_2 probing arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 ...

arm64/sve: Thin out initialisation sanity-checks for sve_max_vl

2018-06-01T14:53:07Z

Now that the kernel SVE support is reasonably mature, it is excessive to default sve_max_vl to the invalid value -1 and then sprinkle WARN_ON()s around the place to make sure it has been initialised before use. The cpufeatures code already runs pretty early, and will ensure sve_max_vl gets initialised. This patch initialises sve_max_vl to something sane that will be supported by every SVE implementation, and removes most of the sanity checks. The checks in find_supported_vector_length() are retained for now. If anything goes horribly wrong, we are likely to trip a check here sooner or later. Signed-off-by: Dave Martin Acked-by: Will Deacon Signed-off-by: Catalin Marinas

KVM: arm64: Remove eager host SVE state saving

2018-05-25T11:28:30Z

Now that the host SVE context can be saved on demand from Hyp, there is no longer any need to save this state in advance before entering the guest. This patch removes the relevant call to kvm_fpsimd_flush_cpu_state(). Since the problem that function was intended to solve now no longer exists, the function and its dependencies are also deleted. Signed-off-by: Dave Martin Reviewed-by: Alex Bennée Acked-by: Christoffer Dall Acked-by: Marc Zyngier Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier

arm64/sve: Move sve_pffr() to fpsimd.h and make inline

2018-05-25T11:28:29Z

In order to make sve_save_state()/sve_load_state() more easily reusable and to get rid of a potential branch on context switch critical paths, this patch makes sve_pffr() inline and moves it to fpsimd.h. must be included in fpsimd.h in order to make this work, and this creates an #include cycle that is tricky to avoid without modifying core code, due to the way the PR_SVE_*() prctl helpers are included in the core prctl implementation. Instead of breaking the cycle, this patch defers inclusion of in until the point where it is actually needed: i.e., immediately before the prctl definitions. No functional change. Signed-off-by: Dave Martin Reviewed-by: Alex Bennée Acked-by: Catalin Marinas Acked-by: Marc Zyngier Signed-off-by: Marc Zyngier